Growth of ZnSnN2 by Molecular Beam Epitaxy

The Zn-IV-N-2 family of materials represents a potential earth abundant element alternative to conventional compound semiconductor materials that are based on gallium and indium. While both ZnSiN2 and ZnGeN2 have been studied to some degree, very little is known about the narrow-gap member ZnSnN2. Here, we investigate the growth dynamics of crystalline ZnSnN2 through plasma-assisted molecular beam epitaxy. All films exhibit some degree of crystalline order regardless of growth conditions, although significant tin coverage was observed for films grown with low Zn:Sn flux ratio; Zn flux in particular became increasingly problematic at increased substrate temperatures designed to improve crystallinity. Single-crystal material was achieved through careful optimization of growth parameters. Regardless of deposition conditions or substrate choice, however, all films exhibit a monoclinic structure as opposed to the predicted orthorhombic lattice; this can be directly attributed to sublattice disorder.